1. Field of the Invention
This invention relates to a novel activated carbon formed body and more particularly to an activated carbon formed body consisting of activated carbon granules and inorganic substance carrier. The invention relates also to a method of producing the activated carbon formed body.
2. Prior Art
As is well known, activated carbon is widely used as an adsorbing body for deodorization or decolourization, as a catalyst for decomposition of ozone and as a carrier for various catalysts. However, the activated carbon is usually provided in the form of granules or pellets but is, in few cases, available in the form of a specifically shaped body.
Granule or pellet type activated carbon cannot be incorporated in its available form into a device as an adsorbing body or a catalyst carrier, and requires a special casing in which, the carbon must be maintained horizontally. Accordingly, the direction of ventilation is limited to a vertical direction and incorporation of the carbon into such a device involves difficulties. Further the method of using the carbon in such a situation is severely limited.
An example of an activated carbon formed body of a specified shape is one in which a mixture of activated carbon powder, such as charcoal and coal, with a bonding agent, such as tar and pitch, is pressure molded, dried at a temperature of about 100.degree. C., carbonized at a temperature of lower than 600.degree. C. and then steamed and activated in an activation furnace. But the fact that the method above uses hard-to-handle pitch and tar, which themselves are changed by activation treatment into activated carbon as a bonding agent, makes it difficult to use various molding methods other than pressure molding. Accordingly if the formed body has a complicated shape as to make passage of steam difficult therethrough, it is difficult to activate the formed body sufficiently far into the interior because activation treatment is effected after completion of the body. This is a fatal defect involved in such a conventional formed body. Presently, there is no alternative but to provide the activated carbon formed body of this type in the form of a plate or a very simple and small shape equivalent to the plate. Thus, it is difficult to obtain formed bodies of various shapes adapted for application of use, particularly, a large-sized body.
An activated carbon formed body of the type different from the above is one in which activated carbon granules are bonded by an organic binder. However, the formed body of this type, because the surface of the carbon granules are bonded by an organic binder, does not have full activating property. Moreover, because the binder deteriorates due to heat and with the lapse of time, the formed body is reduced in strength and lacks practical applicability. This is yet another disadvantage inherent in the formed body of this type.
Yet another actuated carbon body is one in which the surface of a ceramic base is coated with activated carbon granules of a rubber-based or other organic binder. This formed body, in comparison with the preceding body bonded by the organic binder, has high activating properties and little tendency to deteriorate. However, it has a disadvantage in that because the surface of the base is coated with activated carbon granules, the amount of activated carbon granules held is small, with the result that the formed body loses its activating property in a relatively short time of use. An activated carbon formed body equivalent to the type described above has been developed and is used, for example, as activated carbon fiber paper in a corrugated cardboard for use as a filter. Because the material used is paper, however, the formed body changes in shape by the effect of moisture, and is not thus equal to the above-described types in strength. In addition, because the formed body does not have a high content of activated carbon fiber, the body, has a short service life.